Characterization and quantification of apolipoprotein E in the genetically hypercholesterolemic rat (RICO).

Abstract

The levels of apolipoprotein E (apo E) in serum and in isolated lipoprotein fractions from genetically hypercholesterolemic rats (RICO) and their normocholesterolemic controls (SW), were evaluated by immunoblotting, and their polymorphism was analyzed by isoelectrofocusing. The present results confirm previous findings from a qualitative SDS-PAGE analysis. When measured by immunoblotting, total apo E increased by 35% in the RICO rat plasma. In the different lipoprotein fractions, apo E in RICO rat increased in low density lipoproteins; LDL1, LDL2 (apo E rich HDL1) and high density lipoproteins (HDL2, HDL3). Only in the chylomicron fraction did apo E decrease. The two-dimensional electrophoretic method demonstrated that four isoproteins designated E-1, E-2, E-3 and E-4 are present at a pI range from 5.36 to 5.56 in RICO rat as well as in control SW rat.